Silylvinyl groups

This approach does not provide the best control over the number of A arms. It was found that, due to steric reasons, only one of 3.6 silylvinyl groups reacted to produce the miktoarm star. 

The first step of the Pd-catalyzed silylstaimation-cyclization of the 1,6-enyne 115 is silylpalladation of the triple bond to generate alkenylpalladium 117, and the cyclopentane bearing silylvinyl group 116 was obtained via 118. The carbene-Pd complex 119 was the most effective catalyst [35]. 

Table 1.4 Effect of silylvinyl groups on stereoselectivity of C—H bond insertion reported by Davies.

Allenes having a remote carbonyl group react with a silylstannane in the presence of [(7r-allyl)PdCl]2 at RT to give cis-Z-( 1 -silylvinyl)cycloalkan-1 -ols (Table ll).282 Five- and six-membered rings are constructed through the silastan-native coupling. 

Protonation of the A -aryl-Af-(3-triisopropylsilylpropargyl) carbamate 37 with trifluoromethanesulfonic acid generates a (3-silylvinyl cationic intermediate 38 that is attacked by the carbamate carbonyl group (but not the aromatic ring) to give good yields of the 2(3/7)-oxazolone 40 (Fig. 5.9). ... 

We also tested silica gel formation using the trialkoxy-substituted tri(silylvinyl)borazines 3-5. The gel formation was much slower (4 - 5 d) and not complete, i.e. residual alkoxy groups were detected by IR spectroscopy. Also, these materials had a significantly lower specific surface area ( 230m"/g). 

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